Fluorescence laser-scanning microscopy is a well-established imaging technique in biology, available in many imaging facilities to investigate structures within live animal embryos such as zebrafish. Laser scanning microscopes (LSM) are limited when used to study dynamic heart morphology or function. Despite their ability to resolve static cardiac structures, the fast motion of the beating heart introduces severe artifacts in the scanned images and gating the acquisitions to the heartbeat is difficult to implement on traditional microscopes. Furthermore, although alternative high-speed imaging instruments exist, they are not widely available (due to cost or hardware complications), putting dynamic cardio-vascular imaging off-limits for many researchers. Here, we propose a method that allows imaging the beating heart on conventional LSMs. Our approach takes a set of images containing scanning aberrations, each triggered at an arbitrary time in the cardiac cycle, and assembles an image sequence that covers a single cardiac heartbeat. The steps are: (i) frame sorting by solving a traveling salesman problem; (ii) heartbeat duration estimation; and (iii) scan-delay compensation via space-time resampling. We characterize the performance of our method on synthetic data under several light intensities and scanning speeds. We further illustrate our method's applicability on experimental images acquired in live zebrafish larvae, and show that the reconstruction quality approaches that of fast, state-of-the-art microscopes. Our technique opens the possibility of using LSMs to carry out studies of cardiac dynamics, without the need for prospective gating or fast microscopes.

中文翻译：

---

从跳动心脏的非门控和扫描像差激光扫描显微镜图像重建图像序列

荧光激光扫描显微镜是生物学中一种成熟的成像技术，可在许多成像设施中使用，以研究活体动物胚胎（如斑马鱼）内的结构。激光扫描显微镜 (LSM) 在用于研究动态心脏形态或功能时受到限制。尽管它们能够解析静态心脏结构，但跳动心脏的快速运动会在扫描图像中引入严重的伪影，并且很难在传统显微镜上实现对心跳的采集。此外，尽管存在替代的高速成像仪器，但它们并没有广泛使用（由于成本或硬件并发症），这使得许多研究人员无法使用动态心血管成像。在这里，我们提出了一种方法，可以在传统 LSM 上对跳动的心脏进行成像。我们的方法采用一组包含扫描畸变的图像，每个图像在心动周期中的任意时间触发，并组装一个涵盖单个心脏搏动的图像序列。步骤是：（i）通过解决旅行商问题进行帧排序；(ii) 心跳持续时间估计；(iii) 通过时空重采样进行扫描延迟补偿。我们描述了我们的方法在几种光强度和扫描速度下对合成数据的性能。我们进一步说明了我们的方法对在活斑马鱼幼虫中获得的实验图像的适用性，并表明重建质量接近快速、最先进的显微镜的质量。我们的技术开启了使用 LSM 进行心脏动力学研究的可能性，而无需前瞻性门控或快速显微镜。